1. Field
The described aspects relate to wireless networks, and more particularly, to apparatus, methods and systems for multiple bindings having independent forward and reverse link bindings for Mobile Internet Protocols (MIP).
2. Background
Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, 3GPP LTE systems, and orthogonal frequency division multiple access (OFDMA) systems.
Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. This communication link may be established via a single-in-single-out, multiple-in-signal-out or a multiple-in-multiple-out (MIMO) system.
Mobile Internet Protocol is an Internet Engineering Task Force (IETF) standard communications protocol that is designed to allow mobile device users to move from one network to another while maintaining a permanent IP address. As such, MIP serves to allow an access terminal/mobile device to register on foreign networks and connect back to their home network via a combination of a Foreign Agent (FA) and a Home Agent (HA). The HA is responsible for routing data to access terminals currently attached to a foreign network. This is achieved through a tunneling process in which Care-of-Address (CoA) is used to deliver the data to the access terminal. The CoA may be associated with a foreign agent, in which case it is termed FA CoA, or, it may be a co-located CoA meaning the access terminal is allocated an IP address in the foreign network.
Thus, in Mobile IP as the access terminal/mobile device moves from one attachment point, such as a base station or the like, to another attachment point the connection attachment point IP address may change. If the IP address does change, the access terminal sends a binding update to a HA to inform the home agent of the current IP address that is being used by the access terminal. As the access terminal moves from attachment point to attachment point the data packets destined for the access terminal will be routed to the HA first, which, based on the previous binding update, knows which address to send the data packets to. This procedure is transparent to any device which communicating with the access terminal, as only the HA requires knowledge of the access terminal's current IP address.
Applications for Mobile IP such as WiMAX and CDMA2000 networks use a technique termed Proxy MIP (PMIP). In Ultra Mobile Broadband (UMB), PMIP introduces an access gateway (AGW) into the Mobile IP architecture which interacts with the HA on behalf of the access terminal. In PMIP, as the access terminal moves from one attachment point (e.g., a source base station) to another attachment point (e.g. a target base station), instead of the access terminal sending the binding update to the AGW, as is the case in MIP, the target base station acts as a proxy and sends the binding update to the AGW on behalf of the access terminal. The binding update serves to prove to the HA that the entity that performs binding is either the user of the access terminal or a legitimate proxy of the user of the access terminal.
However, in MIP and PMIP, the access terminal is only using one attachment point at any point in time to communicate data. Thus, either the source base station or the target base station is being used by the access terminal at any point in time but not both. In other words, either the source base station or target base station is responsible for sending data to the access terminal on the forward link or receiving data from devices in communication with the access terminal on the reverse link. It should also be noted that after the binding update has been accomplished, the HA/AGW will drop all packets associated with the previous binding even though there may be in-flight packets from the source base station to the HA/AGW.
Recently MONAMI (MObile Nodes And Multiple Interfaces) working group has devised a multiple binding scheme extension for Mobile IP. In the generic concept devised by MONAMI and applied to MIP any base station can send uplink data on the reverse link. Additionally, the MONAMI concepts rely on multiple bindings for the same IP address in which each binding is assigned a weight (i.e., a preference for using the binding compared to other bindings). In the MONAMI concepts any base station can send uplink data on the reverse link but only the base station with the highest weight will receive downlink data on the forward link to send to the access terminal. During the binding process the access terminal communicates binding weights to the HA and based on the binding weights the HA forwards data traffic to the binding with the highest weight. In this regard the data traffic does not flow directly from a target base station when an access terminal moves to a new attachment point/base station because a new binding at the target base station has to be assigned a weight that is higher than the previous one assigned. If the weight assigned to the new attachment point is not higher then the HA will not direct forward link data to the new attachment point. The weighting scheme employed be the MONAMI concepts is unsuitable for this application of moving the data attachment point to the current base station while maintaining the data reception on the reverse direction because while higher weights are required to establish a new forward link, the weight assigned to any one base station cannot increase perpetually.
Additionally, in the MONAMI multiple binding scheme the binding of the forward link and the reverse link are dependent upon one another, i.e., the binding of the forward link affects the reverse link and vice versa. This is because in the MONAMI multiple binding scheme reverse link and forward link are not specified and, therefore, all bindings can receive both reverse link data and forward link data at any time based on the weight of the binding. For example, in a first binding has a weight of 5 and a second binding has a higher weight of 6, the first binding can send reverse link data but will not receive forward link data. However, if all the other bindings have weights less than 5, then the first binding will receive forward link data and send reverse link data. Thus, in the MONAMI multiple binding scheme whether a binding can send forward link data is dependent upon the state of the other bindings.
Therefore a need exists to develop a multiple binding scheme for MIP and derivatives, such as PMIP or the like, that allows for data to be communicated across more than one binding at any point in time and, in particular, allows for multiple base stations to send reverse link data independently of base stations receiving forward link data.